You had asked if anyone ever used floc. I have, prior to full bbb approach, on a very very filthy foreclosure pool. It took two sets of floc after leaf removal, but it did drop the material to the floor so that it could be vacuumed to waste. You have to vacuum very slowly to avoid stirring it back up, and you may have to stop and refill water in order to be able to keep going. You will still stir it up a bit no matter how slowly you go, so plan on a second vacuum session once it resettles.
If you've had so much rain and your pool is on lower ground than your neighbor, I personally would avoid draining-refilling due to the risk that a high water table could cause your liner to float or walls to collapse. If you end up determined to refill, you'd still have to use a plastic sheet to separate the water and refill at the same pace as you drain, so there'd be no real benefit to all that work because you'd still have a lot of sediment left at the bottom, I suspect, or would clog the floor drain.
Even if it's as muddy as the missisipi, it WILL clear, just so you know. Mine did, and it was black!